Could be- wound back intentionally, Entry error by of provider Dash or gauge cluster has been changed

When its a small discrepancy between records which are close in time, I assume it to be that one operator rounds down or forgets the exact reading they just looked at, also look to see if there was an unusual spike upwards before coming down because that would imply an erroneous entry.

If it goes up at regular intervals, then drops down significantly and continues up in the same pattern you can assume the cluster was wound back or replaced.

I had a car that was keyed in wrong at a WOF, but subsequent WOF's after that showed the correct mileage so the line graph does take a sharp nosedive but then shoots right back up at next reading. Easy to explain. If the graph shows a dip then the progression after that is consistent with approx mileage then it's been wound back.

Yeah, probably just a typo. When I last got a wof for my 4wd I needed a recheck. 3 days later and I had supposedly done over 10000km's more. I ended up getting them to fix the reading as they came after me for RUC that I hadn't used. With old readings, see what pattern there is before and after, this can often show where the reading is wrong.

Easily a typo. I sort of work in this area and it happens all the time unfortunately. As intimated by other posters the key is to have a look at the 'pattern' of readings to determine if one is just an error. At the end of the day you can't trust the readings, especially on older cars. New speedo/odo, wound back (less common now days) or replaced with another from a wreckers (possibly legit reason) are just some possible explanations. If its a diesel then its common for the odo to be disconnected at least for periods of time to avoid road user charges.

Always get the car checked out by someone you trust and come to your own conclusions.

Always be yourself, unless you can be Batman, then always be the Batman

The wof report for my car has an impressive drop of 140,000 k's, this is because I had to replace the odometer cluster with a 2nd hand one after the speedo stopped working. It was going to cost several hundred dollars to have the odometer amended to the correct figure which just wasn't in the budget at the time.

1) if the vehicle has a tenths (of km) digit this can sometimes be just read as another digit - result is a reading ten times higher than actual.

Our '71 Super Beetle suffered this exact same issue:

The last reading is 335,242 (Kms?) when the odometer is in Miles and actually read 33,524miles.

Also, when we purchased the bug, it came with spare parts, including a odometer that had a different mileage reading on it.

If you are unsure about a car, don't buy it. And always get second/third opinions. I know what i am looking for when finding issues when purchasing a car, but always either get an AA or MTA check, or one of my mates to look at it.

The AA and MTA checks are well worth the $100 to make sure you dont get stung. One check saved me from spending $5K on a car that was not worth it (car was located in south island, so i was not able to get to it myself)